Infrared copying process and copying material which releases water of crystallization



3,431,412 Patented Mar. 4, 1969 United States Patent Ofice US. Cl.250-65 Claims Int. Cl. G03c 11/22; G01n 23/04, 21/34 ABSTRACT OF THEDISCLOSURE A copying process which comprises preparing a copying elementby applying a compound or a mineral, which releases water ofcrystallization when heated, on a support, placing the element on anoriginal to be copied, subjecting the element and the original totransmittance printing or reflection printing by infrared rays, and thendeveloping the printed copying element by applying developing powdersthereon to give the desired copy. The image density may be increasedwithout any increase in fog density when the exposed element isdeveloped either with a mixture of developing powder and small particlesof surfactant or with a developing powder the particles of which are atleast partially coated with a surfactant.

This invention relates to a copying process and more particularly to theuse of surfactant treated developing powder and to the use of a mixtureof developing powder and a fine solid surfactant for obtaining copiedimages by exposure to infrared rays.

We have provided a new copying process as described in our prior US.patent application Ser. No. 440,062, filed Mar. 9, 1965. According tothis process, a copying element is prepared by applying or vacuumdepositing on a support a compound or a mineral which releases water ofcrystallization when heated by the irradiation of infrared rays. Thiselement is placed on an original to be copied, they are subjected totransmittance printing or reflection printing by infrared rays, and thenthe printed copying element is developed by applying developing powdersthereon to give the desired copy.

The image density of a copy made according to the above mentionedprocess is dependent on the quantity of developing powder adhered at theimage portions. The quantity of developing powder is dependent on theadherence of the developing powder to the image portions correspondingto the pattern of the original of the copying element, said portionsbeing wetted by the Water of crystallization released from the hydrousmaterial of the copying element by being exposed to infrared rays. Whenthe quantity of the developing powder is large, the contrast of imagesobtained is increased, that is, copies are very clear and easy to read.

As the developing powder, any fine powder may be used which has asuitable grain size to adhere to portions of the copying element wettedby the water of crystallization released by heat. Toners used inelectrophotography or electrostatic recording can be used in thisprocess. These are dispersions of pigments in hydrophobic resins and canbe fixed by heating, particularly when the resin is thermoplastic or bybeing subjected to a solvent vapor capable of dissolving the resin. Suchtoners are free of disadvantages, such as hygroscopic properties and areeasy to handle, but in the case of using as a developing improvedprocess for preparing a copy with increasedcontrast.

It is another object of this invention to prepare developing powdersWhich can be used for thermographic copying processes.

We have found as a result of attempts to increase the adherence ofdeveloping powders to image portions that the image density isremarkably increased without increasing fog density (density ofnon-exposed portions after development by developing powder) with use ofdeveloping powder, the surface of which has been treated withsurfactant. Alternatively, we can use a mixture of developing powder andfinely divided solid surfactant.

Surfactants used as wetting agent are suitable for this invention.Illustrative thereof are alkyl sulfosuccinates, alkyl benzenesulfonates, alkyl esters of sorbitan, longchain hydrocarbon quaternaryammonium salts, and alkyl esters of polyoxyethylene sorbitan. When,saponin, a natural wetting agent, is used, the fog density at non-imageportions is remarkably increased.

In the operation of this invention, the surface treatment of developingpowders with the above-mentioned surfactants is carried out bydispersing the commercial developing powder (for example, a finelyground pigmented resinous powder, called toner, sold by Fuji-Xerox Co.,Ltd, Tokyo) in an aqueous solution of surfactants, sub jecting theresulting dispersion to vacuum drying and grinding the dried material toa grain size of 0.1 to g in diameter. When a powder developer is blendedwith a finely divided surfactant, a surfactant that is solid at normaltemperature is finely ground to less than 130 in diameter and mixed witha commercial developing powder.

When a copying element having a support bearing a heat sensitive layerof a colloidal binder and a material having water of crystallization isdeveloped after exposure to infrared radiation by use of the surfactanttreated developing powder, or by use of a mixture of developing powderand fine solid surfactant, a remarkable increase can be found in theimage density without any appreciable increase of fog density. This isdue to the increase in the affinity of the developing powder and water,that is to say, to the fact that the developing powder is readilyadhered to a wetted part corresponding to the image portions of thecopying element.

The invention will be further illustrated by the following examples.

Example 1 Into 200 ml. of water was dissolved 15 g. of gelatin. Into thesolution was added 15 g. of sodium acetate trihydrate and while stirringwas added 20) ml. of ethyl alcohol. In 100 ml. of ethyl alcohol wasdispersed 10 g. of barium stearate, and the thus obtained dispersion wastreated in a ball mill for 12 hours to yield a smooth slurry. Thirtymilliliters of the slurry was added to the abovementioned solution withstirring. Into the solution was added 3 m1. of 6% formaldehyde to obtaina coating solution. Thus prepared coating solution was coated on acellulose triacetate film and dried to yield a copying element havingml. of the solution per square meter.

The thus coated copying element was placed upon an original andsubjected to a reflection printing process by exposing the backof thecoated element to infrared rays. The infrared exposure was conductedusing a Thermofax Model 46 Secretary Copying Machine manufactured bySumitomo-3M Co., Tokyo.

3 4 As a developing powder there was used toner for Xerox 914 OfiiceCopier manufactured by Fuji-Xerox Cot, N d d Fog density 11mg: ai Ltd.,Tokyo. Ten grams of the toner was dispensed in 100 developing e Q04 ml.of 0.75% aqueous solution of sodium dodecylbenzene surfactanttmateddeveloping powder sulfonate (average chain length of alkyl group is12.6). Example 4 The suspension was thoroughly stirred, dried in vacuo,and then comminuted again to less than 88p. in diameter. The py gelement as desel'lbed 1n f ln 2 Was The exposed copying element wassubjected to powder used. A developing powder, the surface ofwhich istreated development by the surfactant treating developing powwltll aSnrfaennt, was P p y treating P by der. The image formed was fixed byheating the copying Welgnt 0f for Xerox 914 Offiee P Wlth element orexposing the copying element to the vapor of P y Welght monolanlate p nAtlas an organic solvent, trichloroethylene. POWdel' Wllnnngton, InSlnnllaf The following results were obtained by measuring the 9 ExampleThe graln SlZe 0f the thus treated transmisison (net) density of animage portion and of a p g Powder e than M- fog portion. (Net densitymeans the density from which 15 when the transInlsSlOn densltles of e pyelement the base density is subtracted.) For the comparison, the Weremeasured after expqsurendevelopmg and fiXlng as fog density and imagedensity were measured when the in Example the followlng (inferences werefound Same copying element and a developing powder not tween densitlesdeveloped with surfactant treated developtreated i s fa tant were useding (powder and developed with non-treated developing 2O POW CI.

Fog density Image density Fog density Image density Non-treated develoln owder 0.02 .35 ff ffff fffi ff if ifn fn 99g; 0,85 5325222135tlifiiitiiadiilgitwas: 333i 313% Example 2 Th 1 Examp 1e 5 d h e copyinge ement was prepare in t e same manner 111i? 116 l ifiisn wf $5.11? lg tb f s ocli ur i $655511? g j g 1 Of ai eyesoutionwasa e o ecoamgsouion.e 332 3 2231 Y g s ZEZQ i g SQ coating solution was coated on acellulose triacetate film 20 g. of barium stearate and the thus obtaineddisperand qned to yleld a copymg element havmg 20 of the sion wastreated in a ball mill for 12 hours to yield a Solutlon Per $.quaremeter smooth slurry Thirty milliliters of the slurry were addeddevelopmg Powder the Surface of lvhlch 15 treated with a surfactant wasprepared by treating one part by to the above prepared solution withstlrrlng to obtain a Weight of a toner for Xerox 914 Omce Copier with 01coating solution. The prepared coating solution was coated part byweight of p 01 y oxyethyl an e Sorbitan monolaurajte gfi g i gg ig fi% ifi g z s fi gi g i ggg ig gzigf (number of ethylenic groups is 12) in asimilari manger to Example 1. The grain size of the thus treate pow er:1.s52:21:22strateg sts: r tiara: an transmisison densities of thecopying element were measwhen the transmlsslon de-nsltles of copymg e19ment ured after exposure, developing and fixing, as in Examwere measuredexpo-smgfldevelopmg and fixmg as ple 1, the following differences werefound between densi- 22 5 25 i f i gggg w gfgggi ggi gg gg: 3 ia a zg sl gg i ggiiggg gg ggs gi ing powder and developed with non-treateddeveloping powder.

Fog density Image density Fog density Image density Non-treateddeveloping powder 0. 03 0.61 Non-treated developing powder 0.03 0. 31Surfactant treated developing powder. 0. 02 0. 85 Surfactant treateddeveloping powder 0. 04 1. 83

Example 3 Example 6 Two hundred milliliters of water was charged to ajuice Into 200 ml. of water was dissolved 5 g. of gelatin. Into mixer,to which 5 g. of gelatin, 5 g. of sodium acetate the solution was added5 g. of sodium acetate trihydrate trihydrate, and a dispersion of 1 g.of zinc palmitate in and, while stirring, was added 40 ml. of ethylalcohol. 50 ml. of ethyl alcohol was added, and stirred to obtain In 100ml. of ethyl alcohol was dispersed 10 g. of zinc a coating solution. Thethus prepared coating solution was palmitate, and the thus obtaineddispersion was treated coated on a cellulose triacetate film and driedto yield a in a ball mill for 12 hours to yield a smooth slurry. Tencopying element having 20 ml. of the coating solution per milliliters ofthe slurry was added to the above-mentioned square meter. 0 solutionwith stirring. Into the solution was added 1 ml. A surfactant treateddeveloping powder was prepared of formaldehyde to obtain a coatingsolution. Thus preby the following procedure. pared coating solution wascoated on a cellulose triacetate Ten grams of a toner for Xerox 914Oifice Copier of film and dried to yield a copying element having ml.Fuji-Xerox Co., Ltd., Tokyo, was dispersed in a solution of the solutionper square meter. containing 100 ml. of water and 1 ml. of 30% aqueous Adeveloping powder, the surface of which is treated solution of sodiumdioctyl sulfosuccinate (Aerosol OT, with a surfactant, was prepared bytreating one part by American Cyanamid Co., New York, N.Y., U.S.A.).weight of a toner for Xerox 914 Office Copier with 0.05 The suspensionwas thoroughly stirred, dried in vacuo, part by weight of dodecyltrimethyl ammonium chloride and then comminuted again to less than88,11. in diameter. in a similar manner to Example 1. The grain size ofthe When the transmission densities of the copying element thus treateddeveloping powder was less than 88;. in

were measured after exposure, developing and fixing, as in Example 1,the following differences were found between densities developed withsurfactant treated developing powder and developed with non-treateddeveloping powder.

diameter.

When the trans-mission densities of the copying element were measuredafter exposure, developing and fixing as in Example 1, the followingdifferences were found be tween densities developed with surfactanttreated developing powder and developed with non-treated developingpowder.

Fog density Image density Non-treated developing powder 0. 01 0. 15Surfactant treated developing powder 0. 03 l. 01

Example 7 Fog density Image density Toner for Xerox 914 Office Copier.Toner mixed with a surfactant It will be understood that changes may bemade in the details of formulation and operation without departing fromthe spirit of the invention, especially as defined in the followingclaims.

What is claimed is:

1. A process for copying Which comprises placing a copying material uponan original to be copied, said copying material being one having asupport bearing a heat sensitive layer of a colloidal binder and thematerial having water of crystallization, subjecting them to infraredexposure to liberate said water in the form of a moist latent imagecorresponding to the original, and developing said moist latent imagewith a developing powder comprising a surfactant.

2. The method of claim 1 wherein said developing powder comprises solidtoner particles the surfaces of which are at least partially coated witha surfactant.

3. The method of claim 1 wherein said developing powder comprises solidtoner particles. mixed with particles of a surfactant.

4. A process as claimed in claim 1, in which the surfactant is a memberselected from the: group consisting of alkyl sulfosuccinates, alkylbenzene sulfonates, alkyl esters of sorbitan, long-chain hydrocarbonquaternary ammonium salts, and alkyl esters of polyoxyethylene sorbitan.

5. A process as claimed in claim 4 in which the alkyl sulfosuccinate issodium dioctyl sulfosuccinate.

6. A process as claimed in claim 4 in which the alkyl benzene sulfonateis sodium dodecylbenzene sulfonate.

7. A process as claimed in claim 4 in which the alkyl ester of sorbitanis sorbitan monolaurate.

8. A process as claimed in claim 4, in which the longchain hydrocarbonquaternary ammonium salt is dodecyltrimethyl ammonium chloride.

9. A process as claimed in claim 4 in which the alkyl ester ofpolyoxyethylene sorbitan is polyoxyethylene sorbitan monolaurate.

10. A process as claimed in claim 3 in which the solid surfactant issodium 3-hexadecyloxypropane-l-sulfonate.

References Cited UNITED STATES PATENTS 3,060,020 10/1962 Greig 250-6213,140,143 7/1964 Kaspaul et al. 346-4 3,196,029 7/ 1965 Lind l171.7

RALPH G. NILSON, Primary Examiner. A. L. BIRCH, Assistant Examiner.

U.S. Cl. X.R. ll7--l.7, 25; 252--62.1

